1. Field of the Invention
This invention relates to differential drive mechanisms, and more particularly, to a mechanical drive mechanism that has plural differentially related outputs responsive to a single rotatory input which causes rotation of three or more rotary outputs that are differentially related, whereby the rotary outputs rotate simultaneously until resistance is encountered on one or more of the rotary outputs causing same to stop rotating until the unloaded outputs encounter resistance, and such rotary outputs will continue to rotate until all of the outputs develop equal torque.
2. Description of the Related Art
A differential drive arrangement is commonly used in a vehicular application. This is a device that divides the input torque from the propeller shaft equally between two output shafts to the drive wheels. Such division occurs irrespectively of whether the drive wheels of the vehicle are rotating at different speeds. Such a speed differential will occur, for instance, on rounding a comer. In applications where the differential divides the input torque equally among the elements that are being subjected to torque, the division occurs independently of the speeds at which they are rotating.
Conventional differential gearing mechanisms have a single input shaft with a pinion gear attached thereto that drives a crown gear fixed to a carrier or cage that contains a set of spider gears or other differentiating mechanism by which two outputs may be derived. If more than two outputs are required, a second differential system in a separate housing is required to be connected in tandem with the first. To maintain an equal distribution of torque at all final outputs, all such differential systems must be assembled such that the two outputs of a primary differential arrangement drives the inputs of two other secondary differential arrangements. As demonstrable mathematically, such an arrangement of differentials results in the total number of outputs being equal to 2.sup.n, i.e., 2, 4, 8, 16, etc. Any other combination of differentials will not yield equal torque outputs.
A standard differential that can develop equal torques will have both bevel gears of same size, and the bevel pinions of equal size as well. In the current state of the art, the provision of four differentially related outputs, as required in a four-wheel-drive vehicle, will require the use of three standard differentials that will be contained in separate but connected casings.
There is a need in the art for a series connection of differential mechanisms that will provide odd or even numbers of outputs, all such outputs being differentially related to each other. There is additionally a need for a multi-output differential drive arrangement that provides equal torques at all outputs irrespective of output speeds.
It is believed that there are no methods or arrangements in the art that provide multiple outputs, e.g., three or more outputs from a single integrated differential mechanism enclosed in a single housing, and that will provide equal or predeterminably unequal torques at all outputs irrespective of the speeds of the output shafts.
It is therefore an object of this invention to provide a system for providing differential action in which more than two differentially related outputs may be derived from a single input.
It is another object of this invention to provide an arrangement that can easily and simply be designed to provide four differentially related outputs from a single input, the arrangement being contained within a single housing, to reduce the size and expense of the arrangement, while simultaneously simplifying placement of the arrangement in various applications.
It is yet another object of this invention to provide differentially geared linear motion as may be required for pressure sensitive leveling operation against uneven and variable density surfaces and providing such capability using only one load sensing device.
It is additionally an object of this invention to provide differentially distributed torque among three or more outputs as may be required in simultaneous tightening of bolts and providing such capability using only one load sensing device.
It is a further object of this invention to provide differentially geared motion to three or more outputs such as, but not limited to, actuation of machine or robotic gripper fingers.
It is still another object of this invention to provide a system of differentially geared outputs to concentric output shafts from a single input shaft through a plural output differential such as may be applied to, but not limited to, multiple output drives in vehicle applications.
A still further object of this invention is to increase power transmission efficiency and durability while reducing in the cost of manufacturing and maintenance.
An additional object of this invention is to eliminate the need for multiple differential housings when providing three or more differential outputs.
Yet another object of this invention is to reduce the number of components required to construct a single differential drive system that provides three or more outputs.